Current RAID disk solutions allow for disk loss without the loss of data. For example, after a loss of a disk (e.g., disk failure), a replacement disk is added to the array. This is generally performed automatically by the RAID controller using a “hot spares” disk already attached to the controller. The replacement disk is used to rebuild the failed disk, thereby recreating the data at the failed disk. However, current rebuilding mechanisms are problematic because during a RAID rebuild the performance of the RAID array is degraded, especially as utilization of the RAID array increases, and the impact becomes greater and greater.
This performance degradation is very noticeable in file systems such as General Parallel File System (“GPFS”) where entire array stripes across all disks are accessed as compared to individual data blocks. In these types of file systems it is possible to keep the array 100% utilized for long periods of time. Thus any rebuilding of the array greatly impacts the performance of the file system because the system's stripping methods results in the system running only as fast as the slowest array. As storage subsystems continue to increase to multi peta-byte levels, the likelihood that at any given time an array is in a degraded state starts to approach 100%.
Therefore a need exists to overcome the problems with the prior art as discussed above.